Temporary implantable medical leads may be used to evaluate the efficacy of stimulation (e.g., neurostimulation) prior to implanting chronically implantable systems within a patient. For example, as a treatment for urinary incontinence, patients may be implanted with a trial percutaneous nerve evaluation (PNE) lead to evaluate the efficacy of sacral nerve stimulation.
Temporary leads that incorporate only one electrode (i.e., unipolar) are used in conjunction with a ground pad. The ground pad is applied to the patient's skin and connected to the electrical stimulation element to complete the electrical circuit. The ground pad may cause the patient discomfort, and can become dislodged or disconnected during the test period, thus preventing test stimulation therapy from occurring. In addition, the temporary lead may migrate, potentially causing the unipolar lead to lose the ability to deliver effective therapy. As a result, higher non-responder rates can occur in patients receiving the temporary lead compared to patients receiving a permanent pacing lead to evaluate the efficacy of stimulation.